Below is based on trolling and vertical fishing water 10' to 100' deep:
I have heard that it does and it doesn't. Tried to test it a few times buts that is kind of a hard thing to do. If it is on and shows fish you know that the fish are or aren't biting with fish near and the fish finder on. If you turn it off you don't know there are fish down there so all you know is you are or are not catching fish with the graph off or vice versa. The previous is not the most well written logical statement and possibly an invalid one but maybe you get the idea.
Try testing it sometime. It is hard to not turn the fish finder back on. So, after briefly testing a couple nights it became very apparent that I would rather see if there are fish near the boat than hope there fish near the boat and know when to stay put, slow down or speed up.
You could find fish and then turn the transducer off but I don't know if that is a fair test if you think about it.
This would be a good question for Dr Sonar. Look him up and give him an ask. If yo do let us know what he said.
My Answer: I don't know.
Good question. I would also like to know yes or no.